#!/usr/bin/python2.4
#
# Copyright 2010 Google Inc.

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

class PersistenceHelper(object):
  def __init__(self, filename):
    self.filename = filename

  def ReadData(self, default):
    if os.path.exists(self.filename):
      return pickle.load(open(self.filename, 'r'))
    return default

  def WriteData(self, data):
    try:
      pickle.dump(data, open(self.filename,'w'))
    except Exception:
      print "Hold on, saving state."
      pickle.dump(data, open(self.filename,'w'))
      sys.exit(1)
      #TODO(robni): skip this nonsense and keep a backup file
